Recently, digital devices including a monitor, a TV, and the like have become larger and been widely used. However, as the digital devices become larger, power consumption is also increased. Accordingly, a digital device capable of reducing power consumption to save energy without degradation in image quality needs to be developed.
In a digital device such as an LCD device, most power is consumed by a backlight portion. Specifically, one-half of the total power is used for the backlight portion. That is, power consumption of the digital device is proportional to brightness of a light source used as backlight and the brightness of the light source depends on a pixel value of an image to be displayed. In addition, the brightness of the light source is determined depending on a maximum pixel value of an area managed by the corresponding light source. Hence, if the maximum brightness of the image is decreased, the brightness of the light source may be decreased, thereby reducing the power consumption of the digital device.
In the related art, a method of linearly decreasing an image pixel value has been used to restrict the power consumption of the digital device. However, the method has the following problems. That is, contrast and sharpness of an image is decreased due to a decreased dynamic range of the image and thus, overall image quality is degraded. In addition, overall brightness of the image is also decreased. As another method, a histogram equalization scheme has been used to restrict the power consumption of the digital device. According to the method, although a certain level of the image brightness and contrast can be secured, the brightness may be changed at an area boundary in case of using a local dimming scheme where the brightness of the light source is adjusted by using the maximum pixel value of the image in a non-uniform manner, which causes problems that artifacts occur and details of a bright part disappear.
Therefore, a digital device suitable for the local dimming scheme for reducing power consumption and minimizing degradation of image quality when a dynamic range is reduced due to decreased image brightness needs to be developed.